SNCM439 鋼の室温高圧水素環境下における疲労き裂進展

概要

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The fracture toughness and the fatigue crack growth properties of heat treated SNCM 439 steel were investigated under high pressure of hydrogen up to 9.9 MPa at room temperature. The results obtained are as follows; (1) The fracture toughness, K_Q value, of the steel in hydrogen was smaller than that in argon independent of heat treatments. K_Q values of the quenched and the tempered steel were smaller than that of the annealed steel in hydrogen. On the fracture of these steels, the stretched zone was not observed in hydrogen but in argon. (2) The fatigue crack growth rate of the steel in hydrogen was larger than that in argon, and K_<Fc> of the steel in hydrogen was smaller than that in argon independent of treatments. The order to hydrogen susceptibility of fatigue crack growth properties increased from the annealed to the quenched and then to the tempered steel. (3) The quasi-cleavage fracture did not occur in argon but in hydrogen on the fatigue fracture surface of the annealed steel. But the amount of the intergranular fracture and the surface roughness of the transgranular fracture in hydrogen were larger than those in argon on the fatigue fracture surface of the quenched and the tempered steels.
1985-06-15